Electronic device comprising an integrated circuit and a capacitance element

ABSTRACT

An electronic device (ICD) comprises an integrated circuit (AIC) and a capacitance element (PIC). The integrated circuit (AIC) is provided with a plurality of circuit contact pairs (CI). The capacitance element (PIC) is provided with a plurality of capacitance contact pairs (CC). A capacitance is present between each of at least part of the capacitance contact pairs (CC). The plurality of capacitance contact pairs (CC) faces the plurality of circuit contact pairs (CI). At least a part of the capacitance contact pairs (CC) is electrically coupled in a pair-by-pair manner to at least a part of the circuit contact pairs (CI).

An aspect of the invention relates to an electronic device thatcomprises an integrated circuit and a capacitance element. Theelectronic device may constitute, for example, a signal processor havinganalog and digital signal processing circuits. Other aspects of theinvention relate to a method of manufacturing such an electronic device,a signal processing apparatus comprising such an electronic device, anintegrated circuit and a capacitance element as such.

An integrated circuit may require one or more so-called decouplingcapacitances, for instance for power supply decoupling in digitalintegrated circuits. A decoupling capacitance prevents the occurrence ofrelatively strong parasitic signals that may cause a malfunctioning ofthe integrated circuit. The decoupling capacitance may have a form that,for example, is similar to that of the integrated circuit, which istypically planar. The article “High density, Low-Loss MOS capacitors forIntegrated RF Decoupling” by F. Roozeboom et al. published in theInternational Journal Microcircuits and Electronic Packaging, 24 (3)(2001) pp. 182-196, describes a decoupling capacitance. The decouplingcapacitance is formed by high density MOS capacitors fabricated in6-inch macroporous silicon wafers.

Furthermore, U.S. Pat. No. 6,222,260 discloses the combination of anintegrated circuit with digital circuitry and a decoupling capacitor ina configuration wherein the decoupling capacitor faces the integratedcircuit.

According to an aspect of the invention, an electronic device comprisesan integrated circuit and a capacitance element. The integrated circuitis provided with a plurality of circuit contact pairs. The capacitanceelement is provided with a plurality of capacitance contact pairs. Acapacitance is present between each of at least a part of thecapacitance contact pairs. The plurality of capacitance contact pairsfaces the plurality of circuit contact pairs. At least a part of thecapacitance contact pairs is electrically coupled in a pair-by-pairmanner to at least a part of the circuit contact pairs.

The invention takes the following aspects into consideration. Anintegrated circuit typically comprises relatively many sub-circuits,such as, for example, logic gates, drivers, or amplifiers. Eachsub-circuit occupies a different location within the integrated circuit.The high-frequency behavior of a sub-circuit depends on the electricalpath that couples the sub-circuit to a decoupling capacitance. The lowerthe impedance of this electrical path, the better the high-frequencybehavior of the sub-circuit will be. The electrical path has arelatively low impedance if the electrical path is relatively short orif the electrical path is relatively wide, or both. The electrical pathwill be relatively short for a sub-circuit that is relatively close tothe decoupling capacitance. However, there may be one or moresub-circuits that are relatively far from the decoupling capacitance.The electrical path can be made relatively wide for those sub-circuitsin order to have a sufficiently low impedance. However, a relativelywide electrical path requires an appreciable amount of surface area,which is not always available in the integrated circuit and which,furthermore, is relatively costly.

In accordance with the aspect of the invention described hereinbefore,the integrated circuit has various circuit contact pairs that facecapacitance contact pairs between which a capacitance is present. Thecircuit contact pairs and the capacitance contact pairs are electricallycoupled on a pair-by-pair basis. Accordingly, individual capacitances inthe capacitive element are coupled individually to the integratedcircuit in a small area. Consequently, there will be relatively manysub-circuits in the integrated circuit that are relatively close to acapacitance, which can be used for decoupling purposes. It is thuspossible for electrical paths, which couple sub-circuits to decouplingcapacitances, to have an average length that is relatively modest. Thisallows the integrated circuit to have a satisfactory high-frequencybehavior. The coupling is preferably established using a solderconnection, and particularly with a solder bump. As a solder material,use can be made of conventional solders on lead or tin basis, but alsoof metals such as gold, copper. Particularly good results have beenobtained with bumps including an immersion soldering layer on the basisof a Sn or a In-alloy, and provided on an underbump metallization ofcopper, nickel or the like. Such bumps can be provided with a very highpitch, up to less than 10 microns. The fact that the distance betweenthe capacitive element and the integrated circuit will be small is not aproblem, since both of them have a semiconductor substrate with at leastcomparable coefficients of thermal expansion.

In a particular embodiment, the integrated circuit comprises analoguecircuits, memories and logic circuits, and the capacitances are coupledto the logic circuit only. Preferably, the capacitive element covers thecomplete area of the logic circuit.

In a suitable embodiment, use is made of trench capacitors, as disclosedin the above mentioned article. The trench capacitors have a very smallsurface area. Moreover, it was found that a bond pad may be provideddirectly on top of a capacitor. Herewith a very dense array of bumps forconnection to the integrated circuit can be provided. In order toprovide a low-ohmic connection and coupling, the integrated circuit isprovided with contact pads that, as seen in perpendicular projection,have a substantial overlap with the transistors. Such a layout is knownper se as a ‘bond pads on active’-layout. Although not needed explicitlyfor the adhesion of bumps, it is preferred herein that the bond pads arepresent on top of the passivation layer of the integrated circuit.

In a most suitable embodiment, the capacitance contact pairs aresubstantially evenly distributed over a surface area of the capacitiveelement. As a consequence, by a most efficient distribution and the useof trench capacitors, the resulting structure has a chessboard patternof inputs and outputs. Generally, the input is a signal pad (V_(ss)),and the output is a ground pad (V_(dd)). As will be understood, thebumps between integrated circuit and capacitive element will have thesame pattern. In this layout, the array of bumps has a coaxialstructure, which is a type of transmission line and has a very lowparasitic impedance.

It is preferred that only part of the decoupling capacitors are providedin a capacitive element separate from the integrated circuit. Suitably,30-60% of the capacitances, and preferably about 50%, are present in thecapacitive element.

The capacitive element can be provided in combination with theintegrated circuit in various ways: as a separate element, or as part ofa carrier or another device.

In a first embodiment, the capacitive element has a surface area that issmaller than that of the integrated circuit. It is then placed on top ofthe integrated circuit, before packaging of the electronic device in aconventional manner. In this embodiment, the shape of the logic circuitshould be as rectangular as possible, and any other circuits, such asthe analogue circuits and the memories if present, should be designed inanother area. These circuits would reduce the effective fill factor ofthe logic circuit, thereby necessitating a larger, more expensivecapacitive element. The separation of the different types of circuitsrequires an amendment of the design of a conventional digital integratedcircuit.

In an alternative embodiment, the capacitive element forms part of aninterposer, and may be the carrier for the integrated circuit. It isthen suitable that this carrier extends laterally beyond the integratedcircuits and comprises further functions such as resistors,interconnects. In this case, the capacitances and the individualconnections are, by preference, still limited to the area of the logiccircuit.

In a further embodiment, not only the capacitive elements are present ina separate chip, but also the memory. In view of the decrease in cost ofthe memory and in view of the use of stacked-die configurations, thereis a trend to separate the memory circuit from the logic circuit, and toput it into a separate device, that is afterwards assembled with thelogic circuit. As trench capacitors are suitable for use in memories aswell, the memory can be integrated with the decoupling capacitors intoone device.

Another advantage of the invention relates to the following aspects. Itis possible to separately manufacture the integrated circuit and thecapacitance element of the electronic device in accordance with theinvention, before they are assembled. Accordingly, the integratedcircuit can be manufactured using a technology that is cost-efficientfor integrated circuits. The capacitance element can be manufacturedusing a different technology that is cost-efficient for capacitanceelements. For example, the integrated circuit can be manufactured usinga standard technology, whereas the capacitance element can bemanufactured in accordance with the technology described in the articlecited hereinbefore. This approach is more cost-efficient compared withan approach in which a relatively complicated technology is used tomanufacture integrated circuits that comprise decoupling capacitances.For those reasons, the invention allows cost efficiency.

These and other aspects of the invention will be described in greaterdetail hereinafter with reference to drawings.

FIG. 1 is a block diagram that illustrates a television set.

FIG. 2 is a cross-section diagram that illustrates an integrated circuitdevice of the television set.

FIG. 3 is a top view diagram that illustrates an active integratedcircuit of the integrated circuit device.

FIG. 4 is a top view diagram that illustrates an alternative activeintegrated circuit.

FIG. 5 is a cross-section diagram that illustrates a passive integratedcircuit of the integrated circuit device.

FIG. 1 illustrates a television set TV. The television set TV comprisesa receiver REC and a display device DPL. The receiver REC comprises aprinted circuit board PCB on which an integrated circuit device ICD andother components are mounted. The integrated circuit device ICD formspart of a signal processing chain that derives a video signal VID from aradiofrequency input signal RF. The display device DPL displays thevideo signal VID.

FIG. 2 illustrates the integrated circuit device ICD. FIG. 2 is adiagrammatic cross section of the integrated circuit device ICD. Theintegrated circuit device ICD comprises an active integrated circuit AICand a passive integrated circuit PIC, which are mounted on a lead frameLFR. A mold compound MLD covers the active integrated circuit AIC andthe passive integrated circuit PIC so as to provide a mechanicalprotection. The lead frame LFR comprises a die pad DPD on which thepassive integrated circuit PIC is mounted. The lead frame LFR furthercomprises various electrical leads LD for electrically coupling theintegrated circuit device ICD to other components. A signal ground leadLD1 and a supply voltage lead LD2 couple the integrated circuit deviceICD to a signal ground GND and a supply voltage VCC, respectively.

The active integrated circuit AIC comprises a logic circuit LGC, amemory circuit MEM, a supply voltage pad VP, a signal ground pad GP, anda conductive shield SHD that is coupled to the signal ground pad GP. Asolder connection SC1 electrically couples the signal ground pad GP tothe signal ground lead LD1 of the lead frame LFR. Another solderconnection SC2 electrically couples the supply voltage pad VP to thesupply voltage lead LD2 of the lead frame LFR. Accordingly, the logiccircuit LGC and the memory circuit MEM may receive the supply voltageVCC from an external source via, for example, supply voltage lines thatare present on the printed circuit board PCB illustrated in FIG. 1. Thelogic circuit LGC may be arranged to process, for example, digitaltelevision signals. To that end, the logic circuit LGC may cooperatewith the memory circuit MEM. For example, samples of a digitaltelevision signal may temporarily be stored in the memory circuit MEM.

The active integrated circuit AIC comprises a plurality of circuitcontact pairs CI1, . . . , CI5, which occupy a surface area Slgc of theactive integrated circuit AIC. When the active integrated circuit AIC isviewed in the direction of the surface area Slgc, the logic circuit LGClies underneath the surface area Slgc and thus underneath the circuitcontact pairs CI. The circuit contact pairs CI are electrically coupledto the logic circuit LGC. For example, each circuit contact pair CI maybe coupled to a different sub-circuit that forms part of the logiccircuit LGC. Preferably, the circuit contact pair CI is physically closeto the sub-circuit to which it is coupled. The circuit contact pairs CIthat are illustrated have a circuit contact that is represented by ablack square, the other circuit contact being represented by a whitesquare. The black square of a circuit contact pair CI may be coupled,for example, to a signal ground path of a sub-circuit. The white squareof a circuit contact pair CI may be coupled to a supply voltage path ofthe same sub-circuit.

The passive integrated circuit PIC comprises a plurality of capacitancecontact pairs CC1, . . . , CC5, which occupy a surface area Scap of thepassive integrated circuit PIC. The capacitance contact pairs CC facethe circuit contact pairs CI. Bump connections BU electrically couplethe capacitance contact pairs CC to the circuit contact pairs CI in apair-by-pair manner. A capacitance is present between each of thecapacitance contact pairs CC. The capacitance that is present between acapacitance contact pair CC will also be present between the circuitcontact pair CI to which the capacitance contact pair is electricallycoupled. The capacitance may thus form a decoupling capacitance for thesub-circuit to which the circuit contact pair CI is coupled. Forexample, the capacitance may constitute a decoupling capacitance betweena supply voltage path and a signal ground path of the sub-circuitconcerned. Accordingly, a sub-circuit can have its own decouplingcapacitance and, moreover, the decoupling capacitance can be relativelyclose.

FIG. 3 illustrates the active integrated circuit AIC. FIG. 3 is a topside view of the active integrated circuit AIC. A cross-sectional lineA-B in FIG. 3 indicates the position of the cross-sectional viewillustrated in FIG. 2. FIG. 3 shows the supply voltage pad VP, thesignal ground pad GP, the memory circuit MEM, and the logic circuit LGCthat form part of the active integrated circuit AIC. FIG. 3 furtherillustrates that the active integrated circuit AIC comprises an analogcircuit ANA. The analog circuit ANA may include, for example, ananalog-to-digital converter so as to convert an analog video signal intoa digital video signal. Each circuit within the active integratedcircuit AIC occupies a different area.

FIG. 3 illustrates that the active integrated circuit AIC comprisesfurther circuit contact pairs CI in addition to those illustrated inFIG. 2. Circuit contact pairs CI are present on substantially the wholearea that the logic circuit LGC occupies. That is, the surface area Slgcthat the circuit contact pairs CI occupy, coincides with the area thatthe logic circuit LGC occupies within the active integrated circuit AIC.FIG. 3 further illustrates that the surface area Slgc that the circuitcontact pairs CI occupy has a substantially rectangular shape.Accordingly, the surface area Scap of the passive integrated circuit PICthat the capacitance contact pairs CC occupy, which is illustrated inFIG. 2, may also have a substantially rectangular shape and may have thesame size. The size of the passive integrated circuit PIC in terms oflength and width may thus substantially correspond to the surface areaSlgc that the circuit contact pairs CI occupy. This is cost-efficient.

FIG. 4 illustrates an alternative active integrated circuit AIC′ thatrequires a relatively large passive integrated circuit, which is lesscost efficient. The alternative active integrated circuit AIC′ comprisesan alternative logic circuit LGC′, two alternative memory circuitsMEM1′, MEM2′, an alternative analog circuit ANA′, and a plurality ofcircuit contact pairs CI′ that occupy a surface area Slgc′. The surfacearea Slgc′ that circuit contact pairs CI occupy substantially coincideswith the area that the alternative logic circuit LGC′ occupies.

FIG. 4 illustrates the smallest possible rectangle SRCT that can cover asurface area Slgc′ which the circuit contact pairs CI′ occupy. Arectangular passive integrated circuit would at least need to have thesize of the smallest possible rectangle SRCT in terms of length andwidth. Let it be assumed that this rectangular passive integratedcircuit PIC has a main face that is substantially filled withcapacitance contact pairs. Only a relatively modest percentage can beelectrically coupled with the circuit contact pairs CI′. In effect,surface areas of the rectangular passive integrated circuit that facethe two alternative memory circuits MEM1′, MEM2′, and the alternativeanalog circuit ANA′, would effectively not be used. It is thereforeadvantageous that the surface area Slgc, which the circuit contact pairsCI occupy, has a substantially rectangular shape as illustrated in FIG.3. It is further advantageous that the circuit that needs to be coupledalso has a substantially rectangular shape and occupies substantiallythe same area as the circuit contact pairs. This allows capacitances ofthe passive integrated circuit to be coupled to sub-circuits in theactive integrated circuit via relatively short electrical paths, whichcontributes to a satisfactory high-frequency behavior.

FIG. 5 illustrates the passive integrated circuit PIC. FIG. 5 is adiagrammatic cross section of a part of the passive integrated circuitPIC. FIG. 5 shows a capacitance contact pair CC on the surface areaScap, which surface area is also illustrated in FIG. 2. The passiveintegrated circuit PIC comprises a pair of electrodes ELI, ELO betweenwhich a dielectric material DLC is present. An inner electrode ELI iselectrically coupled to the capacitance contact represented by a blacksquare. An outer electrode ELO is electrically coupled to thecapacitance contact represented by a white square. The pair ofelectrodes ELI, ELO is substantially perpendicular to the surface areaScap that the capacitance contact pairs CC occupy. Accordingly, it ispossible to obtain a relatively high capacitance per unit of surfacearea. A relatively small surface area is sufficient to obtain arelatively large capacitance, which is typically required for decouplingpurposes. The passive integrated circuit PIC illustrated in FIG. 5 maybe manufactured, for example, using a technology as described in thearticle cited hereinbefore.

The integrated circuit device ICD illustrated in FIG. 2 can bemanufactured in various different manners. For example, the activeintegrated circuit AIC may be manufactured in accordance with aconventional technology, whereas the passive integrated circuit PIC maybe manufactured separately in accordance with a special technology, suchas, for example, a technology as described in the article citedhereinbefore. The passive integrated circuit PIC may be fixed to the diepad DPD of the lead frame LFR. Subsequently, the active integratedcircuit AIC is positioned so that the circuit contact pairs CI face thecapacitance contact pairs CC of the passive integrated circuit PIC.Subsequently, the active integrated circuit AIC is fixed to the passiveintegrated circuit PIC and the lead frame LFR. This can be achieved, forexample, by means of heating solder balls, which are present on thecircuit contact pairs CI, the signal ground pad GP, and the supplyvoltage pad VP. The solder balls that are present on the circuit contactpairs CI will reflow and form the bump connections BU illustrated inFIG. 2.

In accordance with an alternative method, the passive integrated circuitPIC is first fixed to the active integrated circuit AIC so as to obtainan integrated circuit assembly in which the capacitance contact pairs CCface the circuit contact pairs CI. The capacitance contact pairs CC andthe circuit contact pairs CI are electrically coupled to each other on apair-by-pair basis. The integrated circuit assembly is subsequentlymounted on the lead frame LFR.

The detailed description hereinbefore with reference to the drawingsillustrates the following characteristics. An electronic device (ICD)comprises an integrated circuit (active integrated circuit AIC) and acapacitance element (passive integrated PIC). The integrated circuit(AIC) is provided with a plurality of circuit contact pairs (CI). Thecapacitance element (PIC) is provided with a plurality of capacitancecontact pairs (CC). A capacitance is present between each of at least apart of the capacitance contact pairs (CC). The plurality of capacitancecontact pairs (CC) faces the plurality of circuit contact pairs (CI). Atleast a part of the capacitance contact pairs (CC) is electricallycoupled in a pair-by-pair manner to at least a part of the circuitcontact pairs (CI). This allows the integrated circuit to have asatisfactory high-frequency behavior.

The detailed description hereinbefore further illustrates the followingoptional characteristics. The capacitance contact pairs (CC) aresubstantially evenly distributed over a surface area (Scap) of thecapacitance element (PIC). This further contributes to a satisfactoryhigh-frequency behavior.

The detailed description hereinbefore further illustrates the followingoptional characteristics. The circuit contact pairs (CI) occupy asurface area (Slgc) of the integrated circuit (AIC). This surface area(Slgc) has a shape that is substantially rectangular. This allows costefficiency.

The detailed description hereinbefore illustrates the following optionalcharacteristics. The capacitance element (PIC) comprises a pair ofelectrodes (ELI, ELO) that constitute a capacitance between acapacitance contact pair (CC). The pair of electrodes (ELI, ELO) issubstantially perpendicular to a surface area (Scap) that thecapacitance contact pairs (CC) occupy. This allows the capacitanceelement to have a relatively large capacitance per unit of surface,which further contributes to a satisfactory high-frequency behavior.

The aforementioned characteristics can be implemented in numerousdifferent manners. In order to illustrate this, some alternatives arebriefly indicated. It is not absolutely necessary that each of thecircuit contact pairs is coupled to each of the capacitance contactpairs. For example, referring to FIG. 2, let it be assumed that circuitcontact pair CI5 were not electrically coupled to capacitance contactpair CC5. The integrated circuit device ICD may still have asatisfactory high-frequency behavior. Referring to FIG. 2, although theconductive shield SHD will generally contribute to a satisfactoryhigh-frequency behavior, the conductive shield SHD may be omitted inorder to reduce cost. Referring to FIG. 2, although the activeintegrated circuit ACI is mounted on the lead frame LFR in accordancewith a flip-chip technology, which contributes to a satisfactoryhigh-frequency behavior, a different mounting technology may be used,such as, for example, wire bonding. It should further be noted that theelectronic device in accordance with the invention may be applied in anytype of signal processing apparatus. The television set illustrated inFIG. 1 is merely an example. The electronic device may be applied in,for example, a computer or a digital signal processor for processinghigh-speed data.

There are numerous ways of implementing functions by means of items ofhardware or software, or both. In this respect, the drawings are verydiagrammatic, each representing only one possible embodiment of theinvention. Thus, although a drawing shows different functions asdifferent blocks, this by no means excludes that a single item ofhardware or software carries out several functions. Nor does it excludethat an assembly of items of hardware or software or both carry out afunction.

The remarks made hereinbefore demonstrate that the detailed descriptionwith reference to the drawings, illustrates rather than limits theinvention. There are numerous alternatives, which fall within the scopeof the appended claims. Any reference sign in a claim should not beconstrued as limiting the claim. The word “comprising” does not excludethe presence of elements or steps other than those listed in a claim.The word “a” or “an” preceding an element or step does not exclude thepresence of a plurality of such elements or steps.

1. An electronic device comprising: an integrated circuit provided witha plurality of circuit contact pairs and a capacitance element providedwith a plurality of capacitance contact pairs a capacitance beingpresent between each of at least a part of the capacitance contact pairsthe plurality of capacitance contact pairs facing the plurality ofcircuit contact pairs at least a part of the capacitance contact pairsbeing electrically coupled in a pair-by-pair manner to at least a partof the circuit contact pairs
 2. An electronic device as claimed in claim1, wherein the capacitance contact pairs are substantially evenlydistributed over a surface area of the capacitance element
 3. Anelectronic device as claimed in claim 1, wherein the integrated circuitcomprises a logic circuit separate from an analogue circuit, and thecircuit contact pairs are connected to the logic circuit only.
 4. Anelectronic device as claimed in claim 1, wherein the circuit contactpairs occupy a surface area of the integrated circuit, the surface areahaving a shape that is substantially rectangular.
 5. An electronicdevice as claimed in claim 1, wherein the capacitance element comprisesa pair of electrodes that constitute a capacitance between a capacitancecontact pair the pair of electrodes being substantially perpendicular toa surface area that the capacitance contact pairs occupy.
 6. Anelectronic device as claimed in claim 1, wherein the capacitive elementis part of a device that further comprises a memory circuit whichcooperates with the logic circuit in the integrated circuit.
 7. Anelectronic device as claimed in claim 1, wherein the capacitive elementis part of an interposer device that acts as a carrier for theintegrated circuits and is provided with contact pads for coupling to anexternal board.
 8. A signal processing apparatus comprising anelectronic device as claimed in claim 1, and a substrate that couplesthe electronic device to other components of the signal processingapparatus.
 9. A method of manufacturing an electronic device on thebasis of: an integrated circuit with a plurality of circuit contactpairs and a capacitance element provided with a plurality of capacitancecontact pairs, a capacitance being present between each of at least apart of the capacitance contact pairs the method comprising: apositioning step in which the plurality of capacitance contact pairs ismade to face the plurality of circuit contact pairs and a coupling stepin which at least a part of the capacitance contact pairs areelectrically coupled in a pair-by-pair manner to at least a part of thecircuit contact pairs
 10. A capacitance element provided with aplurality of capacitance contact pairs a capacitance being presentbetween each of at least a part of the capacitance contact pairs thecontact pairs being arranged for electrical coupling in a pair-by-pairmanner to circuit contact pairs of an integrated circuit
 11. Anintegrated circuit provided with a plurality of circuit contact pairsthe circuit contact pairs being arranged for coupling in a pair-by-pairmanner to capacitance contact pairs of a capacitance element in which acapacitance is present between each of at least a part of the contactpairs